I'm looking for a good way to mount a temporary, removable horizontal rod holder like a Scotty on my Mirage Outback, without drilling more holes. Scotty sells a Gimbal Mount Adaptor, but it looks to me like this would spin in circles if placed in the current rod holders. Anyone familiar with this item? Any other suggestions??

That's a great find Jerry! I have not seen those before. I use 1-1/4 pvc pipe extensions in the flush rod holders on my OB. When if first cut them to size, they were a little loose and would move around (spin) ...so I just wrapped a few turns of electrical tape around the end that inserts and they don't budge a bit

I'm sure you could use that or come up with a way to insert them firmly so they don't spin.